Heihachi Mishima is a character in Tekken fighting game series created by Bandai Namco Entertainment, serving as its main antagonist. Introduced as the boss character from the first Tekken video game from 1994, Heihachi appears as the CEO/leader of a military firm known as the Mishima Zaibatsu founded by his father Jinpachi Mishima. Heihachi was the protagonist of Tekken 2 and one of the two main characters of Tekken 7 along with his son Kazuya Mishima, furthermore Heihachi was a boss character in two additional main installments of the series. He is opposed by many of his relatives who wish for his death out of revenge and to take over the Mishima Zaibatsu. This happens across the series and one of the creators of Tekken Katsuhiro Harada has called it a "family feud". Heihachi wants to defeat his son and grandson, Kazuya Mishima and Jin Kazama respectively. Heihachi's backstory and motives are revealed in Tekken 7, in which he is killed by Kazuya and thus does not appear in Tekken 8. Heihachi has two known illegitimate children who are playable in the series, the first is the hero Lars Alexandersson, who debuted in Tekken 6; and the second is Reina, who was introduced in Tekken 8, uses some of his moves and has a similar personality, and is later revealed to be also a Devil Gene user as both Kazuya and Jin.

Tekken is a Japanese media franchise centered on a series of fighting games developed and published by Bandai Namco Entertainment. The franchise also includes film and print adaptations.